Colonoscopy is the most widely used primary screening test for CRC in the U.S., and is the final common exam for all screening modalities. Thus, optimizing colonoscopy performance is crucial for CRC screening programs, regardless of initial screening method. The overall goal of Project 2 is the optimization of colonoscopy exams for colorectal cancer (CRC) to deliver screening: tailored to risk (patient-centered), that is efficient & timely (without over-screening), and effective (maximizing the impact of each exam on risk reduction). The specific goal is to identify failures of colonoscopy screening, characterize potentially modifiable factors for failures, and conduct exploratory studies concerning interventions for minimizing failures. Two of the most important problems in using colonoscopy are under-diagnosis (interval cancers despite screening) and surveillance overuse (at more frequent intervals than guidelines suggest); both are failures for an efficient, effective, and patient-centered screening program. Although a relatively common cancer, only a few percent of the population will die from CRC; thus colonoscopy for most patients results in unnecessary risk, expense, and worry without a potential for benefit. However, among those developing CRC, a significant number had a pre-cancer exam which failed to detect/prevent their cancer: possible failures of detection, or potentially, cancers with a different biology which eluded standard detection methods or exam intervals. Our center will address these problems through a series of investigations in a very large, diverse, community-based population: 1. An evaluation of overall patterns of test use including: screening failures, surveillance failures (CRC developing despite surveillance), and surveillance overuse. 2. An evaluation of quality factors associated with screening failures, including establishment of community-based normative values for quality measures (e.g. adenoma detection rates), testing of methods to adjust adenoma detection rates for patient mix to permit valid comparisons between physicians in different practice settings, and investigation of the associations between different rates and the subsequent risk of CRC for the establishment of quality improvement targets in U.S. populations. 3. Investigation of physician, patient, and healthcare system factors related to the failure, overuse, and quality patterns found in Alms 1 and 2 using a recently developed, systematic, multi-step process for implementing effective performance Interventions in health care settings. At the end of this project, we will have: a) overall patterns of test use and failures; b) modifiable variables that predict high, medium and low performers for certain quality measures; c) identified which modifiable variables to target; d) evaluated what interventions stakeholders would support and e) test piloted interventions that have the greatest potential to be effective for each factor.